Automatic discharge means for apparatus for separating materials of different specific gravities



Oct. 16, 1956 J. D. MARTIN ETAL 2,765,836

AUTOMATIC DISCHARGE MEANS FOR APPARATUS FOR SEPARATING MATERIALS OF DIFFERENT SPECIFIC GRAVITIES Filed April 2, 1951 2 Sheets-Sheet 1 24 l/zz HHHHHHHH Oct. 16, 1956 4 J M RT HAL 2,766,886

AUTOMATIC DISCHARGE MEANS FOR APPARATUS FOR SEPARATING MATERIALS OF DIFFERENT SPECIFIC GRAVITIES Filed April 2, 1951 2 Sheets-Sheet 2 TOP 547': T/MER W W M; i m.

1 H m wmfii F 0 N E L i uzwsw f ZZZ T l l L fih W 9 United States Patent C) AUTOMATIC DISCHARGE NIEANS FOR APPARA- TUS FOR SEPARATING MATERIALS OF DIF- FERENT SPECIFIC GRAVITIES John D. Martin, Philadelphia, and Charles S. Westervelt,

St. Davids, Pa., assignors to United Engineers & Constructors Inc., Philadelphia, Pa., a corporation of Delaware Application April 2, 1951, Serial No. 218,880

8 Claims. (Cl. 209-172.5)

This invention relates to improvements in apparatus for separating coal and refuse (or other intermixed materials of differing specific gravities) by the flotation process, and more particularly to that class of apparatus wherein the refuse or other material of relatively high specific gravity, segregated by gravity at the bottom of a suitable formed separating or agitator chamber, is periodically removed by way of a communicating refuse chamber and top and bottom refuse gates, the first of said gates controlling communication between the chambers and the second of the gates controlling the discharge port of the refuse chamber. Apparatus of this class is described, for example, in United States Patent No. 2,222,030.

A principal object of the invention is to provide improved means for conserving the flotation medium, consisting for example of a suspension of sand, magnetite, galena, barite or other suitable medium in water, by limiting to a minimum the quantities of said medium discharged from the agitator chamber with the refuse.

To this primary end, the invention contemplates provision of a means whereby the operations of the top refuse gate to admit the refuse to the refuse chamber may be made responsive to a predetermined quantitative accumulation of the refuse in the bottom of the agitator chamber.

Another object of the invention is to provide a novel control system for the refuse removal means responsive to change of load on a motor, which change results from reaction of a motor driven element on the accumulated refuse in the bottom of the agitator chamber, said reaction occurring only when or after the said accumulation has reached a predetermined maximum.

The devices for achieving the foregoing objects, and others hereinafter appearing, are illustrated in the attached drawings, wherein:

Fig. l is a diagrammatic illustration of the essential parts of separating apparatus including the elements involved in the present invention, and

Fig. 2 is a wiring diagram illustrating the automatic control system.

In Fig. l of the drawings, the reference numeral 1 indicates a conical shell which forms the correspondingly shaped agitator chamber 2. The shell terminates at the bottom in a cylindrical extension 3, and at the bottom of this extension is a refuse chamber 4. Communication between the extension 3 and the refuse chamber 4 is controlled by a top refuse gate 5, and a similar gate 6 controls-the bottom or discharge port of the refuse chamber. The gate 'is operated by a piston 7 in an hydraulic cylinder '8; and the gate 6 is operated by a piston 9 in a similar cylinder 11. Mounted for rotation in the-chamber 2 is an agitator 12, this agitator being operated by an electric motor 13 through suitable reduction gear 14.

In so far as described the apparatus is conventional, and its mode of operation. is well understood. It is sufficient to say that the chamber 2 contains a suitable flotation medium consisting for example of sand and water, the sand being held in suspension in part by action of the agitator 12 and in part by other means not immediately involved in the present invention. Raw coal is introduced at the top of the cone 1 at the surface ofthe fluid mass in the latter, and the good coal, being of lower specific gravity floats on the flotation medium to a point of discharge from the cone. All material introduced with the coal which is heavier than the fluid mass sinks to the bottom of the cone, and the gates 5 and 6 are automatically periodically operated first to admit the waste material or refuse to the chamber 4, while the gate 6 is closed, and then to discharge the refuse from the chamber while the gate 5 is closed. In this automatic operation the gates are held open for the lengths of time required to fill and empty the refuse chamber. Water and sand lost from the agitator chamber during these refuse removal operations are replaced by means not shown and forming no part of the present mvention.

In accordance with the present invention, and as shown in Fig. 1, the agitator 12 includes an arm 16 which extends downwardly into the refuse collection zone. When the refuse deposit has built up in the bottom of the cone to an extent bringing it into contact with the arm 16, an additional or abnormal load will be imposed upon the agitator motor 13. This factor is utilized as a medium for automatic control of the refuse removal mechanism. To this end, a current transformer 17 is in stalled in the circuit 19 of the agitator motor 13, the secondary 21 of the transformer being connected to a relay 22 which operates at a predetermined amperage, regulated by a rheostat 23, to close a set of normally open contacts 24, 24. Closing of the contacts 24, 24 initiates a gating cycle in which the gates 5 and 6 are automatically operated as described above to remove accumulated refuse from the bottom of the cone.

More specifically, the sequence of operations is as follows:

Assuming that the refuse chamber 4 has been emptied, subsequent closing of the bottom gate 6 is followed by feed of water to the said chamber to fill the latter. This is accomplished by opening of a water feed valve 25 in a supply line 26 by an hydraulic actuator 27 which operates also to close the valve after a predetermined period of time sufl'icient to fill the chamber with water. These operations of the actuator 27 are controlled by a solenoid actuated valve 28, the solenoid being indicated at 29. The period of time during which the valve 25 remains open is regulated by timing means associated with the solenoid 29 as hereinafter described.

The gates remain closed until accumulation of refuse in the bottom of the chamber 2 loads the agitator motor to the point where the relay 22 is actuated to close the contacts 24, 24 thereby initiating operation of the piston 7 to open the gate 5. The operations of the piston 7 to open and close the gate 5 are controlled by a solenoid actuated valve 31, the solenoid being indicated at 32. Under regulation of timing means associated with the solenoid 32, as hereinafter described, the gate 5 will remain open for a suflicient length of time to insure filling of the chamber 4 with refuse from the accumulation in the bottom of the cone 1, and will then close. The bottom gate 6 will now open. This gate will remain open until the refuse has discharged from the chamber 4 and will then close so that the cyclemay be repeated. The operations of the piston 9, which operates the gate 6, are controlled by a solenoid actuated valve 33, the solenoid being shown at 34.

By further reference to Fig. 1 it will be noted that a limit switch 35 is operatively associated with the piston 7;

'be performed automatically by means of the electrical control system shown in Fig. 2. The system is energized when the switch 37 is ciosedas shown. Assuming again that the refuse chamber '4 is empty and that the gate 6 has closed so that the apparatus is as shown in Fig. 1, current now flows to water feed-valve timer 38. Timers of the character illustrated are well known in the art and require no detailed description here.- It will suffice to say that When'the'solenoid'39 is energized it engages a'mechanical clutch (not shown) which connects the-motor M to timer mechanism and the motor is simultaneously started to begin the timing cycle. At the same time relay 41 is energized which closes normally open contacts 42, 42, energizes the solenoid 29, and opens water feed-valve 25 through control valve'28 and actuator 27.' Water'now flows to the chamber 4 and Will continue until the end of the timing period when motor switch 43 of timer unit opens, stops the motor M, and terminates the timing period. At the same time normally-closed contacts 44, 44 of the timer unit are opened, deenergizing relay 41, reopening contacts 42, 42, and deenergizing water feed valve solenoid 29 which returns valve 23 to its original position and, through actuator 27, closes water feed valve 25. Simultaneously, with the opening of contacts 44, 44 normally open contacts 45, 45 of the timer unit are closed, which energizes relay 46 and thereby closes normally open contacts 47, 47 for a purpose described below. The system is now in condition for the gating operations when sufficient refuse has collected in the cone to produce the predetermined load on the agitator motor that will actuate the relay 22 and close the contacts24, 24. When the motor is thus loaded and the contacts 24, 2 closed, the top gate timer 48 is energized, the timer solenoid 49 engages a mechanical clutch (not shown) which connects the timer motor 51 with the timing mechanism and simultaneously starts the motor to initiate the timing are holding contacts which when'closed serve tokeep the timer energized when contacts 24, 24 reopen due to.

reduction of load on agitator motor when refuse drops into refuse chamber 4 after top gate 5 has opened. Closing of contacts 53, 53 energizes relay 54 and thereby closes normally open contacts 55, 55 with resultant energization of top gate solenoid 32 which adjusts valve 31 to actuate piston 7 to open the gate. 7

As the top gate opens the top gate limit switch 35 is immediately moved to open position which segregates the bottom gate timer 56 and control system from the source of electrical energy and makes operation of the bottom gate impossible until the top gate and limit switch have been closed.

At the end of the timing period the top gate timer will operate to close momentarily the normally open timer contacts 57, 57 and will thereby'energize relay 58. This relay is operatively connected with normally open contacts 59, 59 and, when energized will close these contacts to maintain the circuit through the relay and to keep the relay energized. This relay also closes normally open contacts 61, 61 which will permit flow of current to the bottom gate timer 56 after the top gate limit switch 35 has been closed. Since closing of the latter switch is dependent upon closing of the top gate, immature opening of the bottom gate is precluded. Relay58, when energized, will also open normally closed contacts62,.62;

and will thereby make energization of top gate timer impossible. p y,

When the top gate'timing period has beenended, the top'gate timer will also reopen contacts '53, 53', thereby deenergizing relay 54, reopening contacts 55,55," and deenergizing top gate solenoid 32 which will then operate by spring actionto readjust valve 31 to actuate piston 7 so as to return the gate 5'to closed position. The timer 4% also operates at end of the timing period to reopen holding contacts 52, 52, resetting the timer mechanism. When the top gate closes it will also close the top gate limit switch 35 and will thereby energize the bottom gate timer 56, this by reason of the previous closing of the normally open contact 61, 61, as previously described. When the bottom gate timer is thus energized it will engage a mechanical clutch (not shown)fwhich connects the timer motor 63 to the timer mechanism and starts the motor to initiate the timing period. The timer holding contacts 64, 64 are closed to maintain the timer. energized when the contacts 61, 61 reopen; and normally open contacts 65, 65 of the timer will also close. Closing of these contacts energizes relay 66 thereby closing normally open contacts 67, 67, which are operatively associated with the relay 66, and thereby energizing the bottom gate solenoid 34 which, through valve 68, will actuate piston 9 to open the bottom gate 6. i i

When the bottom gate opens the bottom gate limit switch 36 will also open and the water feed valve timer mechanism willbe reset. The opening of the bottom gate limit switch will also 'deener'gize relay 46 thereby reopening contacts 47, 47 with which the relay is associated. Relay 58 will also be deenergized and will thereby reopen associated contacts 59, 59 and contacts'61, 61, and will reclos'e contacts 62, 62. It is now impossible to energize top gate timer 48 or to open the top gate 5.

When the timing period has been completed the bottom gate timer will reopen timer contacts 65,65, thereby deenergizing relay 66 and reopening associated contacts 67, 67. Opening of these contacts deenergizes the bottom gate solenoid 34 which then operates by spring action and through the valve 68 to actuate piston 9 to close the bottom gate. thereby resetting timer mechanism.

When the bottom gate closes, the bottom gate limit switch will also close thereby reene'rgizing the water feed- 7 7 been described above specifically in its relation to a coal cleaning process, the invention is equally applicable to separation of other materials'of differing specific gravie ties, and that the use of the term refuse in the specification and claims is to be understood to embrace generally the materials of relatively high specific gravity which settle to the bottom of the separating chamber during the separating process.

We claim: j V p 1. In apparatus for separating materials of different specific g'ravities in a fluid separating med ma ra d apparatus' including a separating chamber having] a bottom discharge opening, and means for regulating discharge of the materials of higher specificgravities through said opening, the combination with said regulating means of Holding contact 64, 64 will also open.

Losses of fluid medium fromthe agitating cham-.

aveasse a member extending downwardly into said chamber from the top thereof to the bottom discharge zone, and a motor for causing said member to move continuously Within said zone, said motor comprising means responsive to variations in the loading of said motor means in the operation of said member for controlling the operation of said discharge regulating means.

2. In apparatus for separating materials of different specific gravities in a fluid Separating medium, said apparatus including a separating chamber having a bottom discharge opening and normally closed gate valve means for controlling said opening, the combination with gate valve operating mechanism, of means including devices for actuating said mechanism in response to a predetermined accumulation of refuse in the bottom of said chamber for efiecting intermittent discharge of accumulated refuse from the chamber, said actuating devices comprising a primary actuator directly responsive to the said predetermined refuse accumulations for effecting discharge of the refuse and including a driven element reactive with the accumulated refuse only after the latter has reached a predetermined level in the separating chamher, a driving motor for said element, and means responsive to variation in the load imposed upon the motor as a result of the reaction of said element with the refuse for actuating the said valve operating mechanism to effect said discharge, and secondary actuator means responsive to operation of the primary actuator for subsequently automatically actuating the valve operating mechanism to interrupt said discharge.

3. Apparatus according to claim 2 wherein the actuating means comprises devices for regulating the time elapsing between the operations of the primary actuator and the secondary actuator means.

4. Apparatus according to claim 3 wherein the motor of the primary actuator is an electric motor and the said actuating means comprises an electrical control system including a system-controlling switch, and an electric actuator for said switch responsive to increases in current consumption by said motor when loaded.

5. Apparatus according to claim 4 wherein the said actuator for the system-controlling switch comprises a current transformer installed in the motor circuit and subject to variations in current resulting from changes in the load upon the motor, and a relay connected to the secondary of said transformer, and operatively connected to the said switch.

6. Apparatus according to claim 5 wherein the said 6 transformer secondary circuit includes a rheostat for reguiating the actuations of said relay in accordance with a predetermined loading of tire motor.

7. In apparatus for separating materials of different specific gravities in a fluid separating medium, said apparatus including a separating chamber and a communicating subjacent refuse chamber, gate valves operative in sequence to control the passage of accumulated refuse from the bottom of the separating chamber to the refuse chamber and the subsequent discharge of the refuse from the refuse chamber, and means including a control system for operating the valves in cycles for intermittent removal of refuse from the apparatus; the combination with said control system of means responsive to a predetermined accumulation of refuse in the bottom of the separating chamber for initiating said cycles, said means including electric motor driven agitator means in the separating chamber, said agitator comprising an element extending into the refuse accumulation zone in the bottom of the chamber for reactive engagement with the refuse when the latter has reached the predetermined level, a current transformer in the motor circuit subject to variations of current resulting from varying loads on the motor, and electrically actuated means operatively connected to the secondary of said transformer and with said control system and operative at a predetermined amperage in said secondary to initiate a cyclic operation of the gate valves.

8. Apparatus according to claim 7 wherein the said secondary circuit includes a rheostat for control of the current passing to the electrically actuated means.

References Cited in the file of this patent UNITED STATES PATENTS 1,265,734 Brunker May 14, 1918 1,442,042 Boddie Ian. 16, 1923 1,686,435 Chance Oct. 2, 1928 1,894,020 Chance Jan. 10, 1933 2,100,848 Hardgrove Nov. 30, 1937 2,213,352 Stevey Sept. 3, 1940 2,222,030 Hague Nov. 19, 1940 2,232,545 Lum Feb. 18, 1941 2,336,434 Wurzbach Dec. 7, 1943 FOREIGN PATENTS 280,122 Great Britain Oct. 31, 1927 396,558 Great Britain Aug. 10, 1933 

